In the construction of naturally lit structures, such as greenhouses, pool enclosures, solar roof collectors (e.g., photovoltaic modules), stadiums and sunrooms, glass panel roofs have been employed to allow natural light to shine therein. The glass panels themselves can be mounted in frame-like enclosures that are capable of providing a watertight seal around the glass panel and provide a means for securing the panel to a structure. These frame-like enclosures also provide for modular glass roofing systems that can be assembled together to form the roof.
Glass panel roofing systems generally provide good light transmission and versatility. However, the initial and subsequent costs associated with these systems limits their application and overall market acceptance. The initial expenses associated with glass panel roofing systems comprise the cost of the glass panels themselves as well as the cost of the structure, or structural reinforcements, that are employed to support the high weight of the glass. After these initial expenses, operating costs associated with the inherently poor insulating ability of the glass panels can result in higher heating expenses for the owner. Yet further, glass panels are susceptible to damage caused by impact or shifts in the support structure (e.g., settling), which can result in high maintenance costs. This is especially concerning for horticultural applications wherein profit margins for greenhouses can be substantially impacted due to these expenditures.
As a result, multiwall polymeric panels (e.g., polycarbonate) have been produced that exhibit improved impact resistance, ductility, insulative properties, and comprise less weight than comparatively sized glass panels. As a result, these characteristics reduce operational and maintenance expenses. Polymeric panels can also be formed as solid panels. Solid panels are solid plastic between their front and rear faces, and are useful where high impact resistance, high clarity, and/or the ability to thermoform the panel is desired. Multiwall panels have voids between their front and rear faces, e.g., the panel may be extruded as a honeycomb with an array of passages extending along the extruded length of the panel. Multiwall panels are useful where a high insulation value, lightweight, and easy installation, are desired.
For ease of design and assembly, multiwall panels can be produced in modular systems. The modular systems comprise multiwall panels with integral panel connectors, wherein the panel connector assemblies are employed to join the panels together and/or secure the panels to a structure on which they are employed. Standard panels can also be used, which are formed continuously and uniformly, i.e., they are extruded slabs and are cut to size and installed in the same manner as glass. These standard panels require a frame or the like to hold them in place.
Modular panels are advantageous for their extreme ease of installation, but are disadvantageous owing to their limited versatility in that modular panels cannot be cut to a desired size if such cutting involves loss of a connecting edge, because the modular panel will no longer be readily connectable to other panels at the cut edge. As a result, if a panel with an unusual or non-standard width is desired, a new extrusion die must be commissioned, at great expense, so as to be able to extrude panels of the desired width, and having the desired connecting edges. Further, modular panels are naturally limited to use with modular panels having complementary attachment structure (i.e., a tongue-and-groove panel will connect to other tongue-and-groove panels having the same tongue/groove configuration, but will not connect to standing seam panels). Standing seam generally refers to a panel with an integrated side collector adjoined to another panel with the use of a connection system. Thus, greater flexibility in the size of the modular panels, without the requirement for expensive equipment and retooling, and the ability to connect to a variety of panels is desired.
Additionally, modular panels can be subject to high wind loads depending upon the structure and location on which they are installed, and must be able to withstand certain live loads (e.g., wind loads) and static loads (e.g., snow loads) in order to satisfy various building codes (e.g., be able to support 3 feet (0.9 meter) of wet snow and/or be able to withstand wind loads of 80 miles per hour (mph) to 280 mph (130 kilometers per hour (kph) to 450 kph)). Wind loads can create negative forces which can pull a modular panel off its supports and thus, lead to premature failure of the modular panel. An improved connector assembly that can withstand high wind loads and not allow a panel to be pulled from its supports is continually desired.